#include <iostream>
#include <math.h>
#define p sqrt(base*base+height*height)
//p is hypotenuse of my triangles
using namespace std;

int main()
{
    int sum=0, r, base, height;
    cin>>r;
    height=r-1;

    for (base=1; base<r; base++)
    {
        while(p>r)
        {
            height--;
        }
        sum+=height;
    }
    sum*=4;
    cout<<sum<<endl;
}